Royal Mail has been fined €55m (£40m) by the French authorities for its GLS parcel subsidiary’s role in colluding on prices.

The punishment was part of €671m of fines imposed on 20 companies and the TLF trade association for cooperating on annual price increases for parcel deliveries from 2004 to 2010.

The fine draws to a close to a process lasting almost 18 months after the French competition regulator, the Autorité de la Concurrence, said it had found evidence of competition violations.

Royal Mail was one of several companies fined for discussing prices at meetings of the trade association, resulting in reduced competition and a detriment to customers.

The regulator said: “Meetings were organised regularly before and after new pricing rounds, which enabled the companies to homogenise their price demands and secure their commercial negotiations. The discussions were kept secret and there was no official record taken.”

Royal Mail said it accepted the watchdog’s judgment and that its fine was reduced by 18% because it cooperated.

Royal Mail said: “Royal Mail recognises the absolute need to comply with European and national competition law and the necessity to prevent infringements. It has implemented an enhanced compliance programme in GLS France in order to strengthen the culture of competition law compliance.”

The potential fine was first announced in July 2014, less than a year after Royal Mail was privatised, and caused concerns among investors. Royal Mail said the cost was covered by a provision in its accounts for the financial year that ended in March.